Recently, a lighting fixture equipping a human body detection sensor for lighting by detecting a human and an illuminance sensor for performing a lighting control according to peripheral brightness has been prevailed outside a house and at a side surface of a house for the purpose of saving electricity and security (FIG. 1). Such a lighting fixture used except a living space usually employs incandescent lamps in combination, which are simpler and less expensive. However, the incandescent lamps have low energy conversion efficiency from electricity to light. In addition, light to be let in is turned on while saving electricity by dimming light when no one is present.
FIG. 2 illustrates a constitution example of a lighting fixture with a sensor having a function for dimming an incandescent lamp used at a side surface of a house. A lighting fixture 20 is composed of a translucent cover 21, a waterproof cover packing 22, a lamp fitting 23 and a flange 24 for supporting the cover 21 and packing 22, and a socket 25 for a lighting load 1. The flange 24 is provided with a lighting device therein for an on-off control of lighting. In addition, the flange 24 is provided with a sensor unit 26 protruded therefrom at a lower portion equipped with an infrared sensor for turning on the lighting load 1 by detecting a movement of a human and an illuminance sensor for a lighting control according to peripheral illuminance, thereby reading changes of lighting into a load controller inside the lighting device.
For example, when a value read by the illuminance sensor corresponds to brightness in the daytime, the lighting load is configured to be in an off state regardless of a presence of a human, and when peripheral illuminance becomes arbitrary darkness, the incandescent lamp is controlled to dim with 30% of brightness. Furthermore, when the infrared sensor detects a movement of a human while dimming with 30% of brightness, the incandescent lamp is controlled to light with 100% of brightness. Furthermore, the lighting device has a function to turn off the lighting load again when determining that an arbitrary time has been passed and midnight has come, and to light the lighting load with 100% of brightness only when someone is present.
FIG. 3 illustrates a constitution example of a dimming-control circuit using a switching element used for such a lighting fixture. FIG. 4 illustrates a specific circuit example of FIG. 3. The circuit of FIG. 4, of which a specific explanation will be described later in an explanation of FIG. 12, is configured that a load controller 5 outputs a trigger signal at a predetermined phase angle based on a power supply phase signal detected by a power supply phase detector 4, and a load drive unit 3 configured with a switching element such as a TRIAC element TR is phase-controlled, so as to drive the lighting load 1 by a commercial ac power supply AC.
Operations of the load controller 5 and the load drive unit 3 in an on state of the TRIAC element TR are described with reference to FIG. 5. The load controller 5 normally maintains an output to the load drive unit 3 at an H-level during a condition that the lighting load 1 is not turned on. When the TRIAC element TR is turned on, i.e. the lighting load 1 is turned on, a trigger waveform is configured to be a pulsed L-level from a timing after a predetermined phase period T1 (e.g. 9 milliseconds) since a timing when output of the power supply phase detector 4 is converted from an H-level into an L-level, to a timing after a pulse period T2 (e.g. 500 microseconds). Thus, a transistor Q2 of the load drive unit 3 is turned on, and the TRIAC element TR is turned on by applying a trigger current. Immediately after turning on, the lighting load 1 composed of the incandescent lamp as a resistive load is applied with a sine-wave current.
As a result, it is possible to perform the dimming-control by controlling the period T1 and the period T2 by the load controller 5. For example, an effective value of an input current of the incandescent lamp as a resistive lighting load is to be proportionally increased by gradually shortening the period T1 and prolonging the period T2. Therefore, the lighting load is turned on by controlling brightness from 0% toward 100%.
In addition, FIG. 6 illustrates a constitution example of the dimming-control circuit additionally provided with a sensor function. Note that, fundamental operations with regard to lighting of the lighting load are as described above. The load controller 5, to which a sensor unit 7 is connected, determines how and when the lighting load 1 should be turned on according to e.g. logical disjunction/logical conjunction of each sensor signal obtained from a lighting condition setting portion and the sensor unit 7.
The lighting fixture used outside a house or at a side surface of a house has been used employing the lighting device equipped with the incandescent lamp in which the dimming-control can be performed such a resistive lighting load, and the switching element such as a TRIAC element, in combination with the sensor. While, in recent years requiring saving electricity, a lighting fixture using a fluorescent lamp with higher energy conversion efficiency and longer life compared with the incandescent lamp has been increasingly used. Actually, in such a situation, a lighting load such as a bulb-type fluorescent lamp (refer to FIG. 36) that is configured to have a similar size and shape to the incandescent lamp and can be directly attached to a socket for the incandescent lamp has been developed. For example, PTL 1 and 2 disclose lighting devices in which such a bulb-type fluorescent lamp is phase-controlled.
However, when the dimming-controlled resistive load (such as the incandescent lamp) is directly replaced to the capacitive load (such as the bulb-type fluorescent lamp) and then the above-mentioned phase control is performed, there is a problem of the bulb-type fluorescent lamp that is not lighted although the incandescent lamp is lighted, and also a problem of a gap in a lighting start time between the incandescent lamp and the bulb-type fluorescent lamp, at performing the dimming-control. This is because of a property of the capacitive load such as the bulb-type fluorescent lamp in which an input current is not applied, i.e. the lamp is not lighted, until an input voltage reaches a certain level, while the incandescent lamp is applied with an input current in proportion to an input voltage.
FIG. 7 illustrates a basic constitution example of the bulb-type fluorescent lamp represented by the capacitive load. The constitution example includes a rectifier at power supply input portions, which is composed of a diode bridge DB or the like, and an electrolytic capacitor Ci for smoothing a rectified output of the rectifier. The also includes an inverter IV for lighting a fluorescent lamp FL by energy stored in the electrolytic capacitor Ci. A relationship between an input voltage and an input current has a waveform illustrated in FIG. 8. The input current is to be applied when voltage Vci of both terminals of the electrolytic capacitor Ci reaches to a predetermined voltage (refer to PTL 1).
FIG. 9 illustrates a relationship between the input voltage and a lighting condition when a lighting control of the capacitive load such as the bulb-type fluorescent lamp is performed in the above-mentioned lighting device for performing the dimming-control to the resistive load. A trigger signal in this figure has a waveform in the case where the lamp is lighted by the dimming-control so as to increase the amount of light from 0% to 100% if this is the case of the incandescent lamp. With regard to a position of a trailing edge where the trigger signal is changed from an H-level to an L-level, a phase of the power supply voltage is shifted from an “f” point (approximately)180° to an “e” point (0° side). The bulb-type fluorescent lamp cannot be lighted after applied with the trigger signal even if the trigger signal is applied at a trailing edge where a current is not applied to the bulb-type fluorescent lamp, i.e. the power supply voltage is low. The lamp is not lighted until the trailing edge phase of the trigger signal is shifted to a voltage position (“g” point) where the bulb-type fluorescent lamp can be lighted due to the dimming-control.
Due to such a phenomenon, when, for example, it is assumed that the bulb-type fluorescent lamp can be lighted at the phase 70° and the trailing edge phase of the trigger signal is automatically shifted at intervals of 2° degrees, the lamp is to be lighted after 35 cycles of 8.3 ms, i.e. the lamp is lighted after a delay of approximately 0.3 seconds even if the phase is shifted by every half cycle of the input voltage of a 60 Hz cycle (120 Hz). In this case, a lighting fixture with an infrared sensor, for example, is lighted after a human moves through a distance of 1.5 m even if the trigger signal is applied by detecting the human when it is assumed that the human moves at 5 m/s. As a result, a user feels a lighting delay of the bulb-type fluorescent lamp compared with the incandescent lamp.
Actually, the inverter IV instantly operates when the trigger signal is applied at a phase where the voltage Vci is higher than a predetermined voltage in a phase of more than 90° of a power supply voltage according to a relationship between the electrolytic capacitor Ci and the input voltage. However, the electrolytic capacitor Ci is not charged and a flickering phenomenon may be caused since the voltage Vci is immediately reduced. Therefore, for example, in a case of a mode of keeping lighting by dimming light at a certain level, the incandescent lamp is lighted by dimming light. However, the bulb-type fluorescent lamp may cause a repeated flickering phenomenon.
Thus, troubles due to such a load difference have been dealt with generally by being configured that each lighting device has its own control method, or by being configured that a selector switch is provided so as to select a load that a user uses. However, when employing such measures, there are problems of a regulated arrangement of the lighting device inside the fixture and complexity of the constitution of the lighting device caused by providing such a switch in the lighting device. Moreover, the recent lighting load is hard to determine apparently whether the load is a resistive load or a capacitive load when an LED is employed for the lighting load, for example. Also, it is extremely difficult for a user to judge the difference.
The present invention has been made focusing on the above-described problems. An object of the present invention is to provide a lighting device and a lighting fixture for performing a lighting control of a lighting load by a switching element, in which a user can freely select a lighting load and does not need to intentionally set the lighting device corresponding to the selected lighting load, and a lighting control can be achieved according to each load characteristics.
Citation List
Patent Literature
    [PTL 1] Japanese Patent Application Laid-Open Publication No. H11-135290 (published in 1999).    [PTL 2] Japanese Patent Application Laid-Open Publication No. H11-111486 (published in 1999).